The present invention relates to power supplies and, more particularly, to a novel power supply circuit for controlling the duty-cycle of and, hence, the magnitude of current flowing through, and power generated by, a magnetron microwave generator in a microwave oven and the like power-consuming loads.
In microwave ovens and the like, wherein the amount of power supplied, such as the microwave power supplied by a magnetron and the like generators, to a load must be varied to facilitate different power-consumption schedules, such as the different cooking schedules requiring differing amounts of microwave power, it is desirable to be able to energize the generator, e.g. the oven magnetron, to the power-producing condition with a variable duty cycle. To prevent abnormal wear of mechanical components utilized to switch primary power to the power supply transformer, it is desirable to have the power supply transformer remain in the energized condition throughout the power-supplying interval, and to control the percentage of time, during each unit of time, during which the generator is enabled to provide energy to the load, e.g. the contents to be heated in the microwave oven.